Barrier walls and flood walls can be formed from a plurality of elongated, vertically-oriented piles driven completely into the earth, or to a depth sufficient to support the piles in an upright orientation above the earth. In some cases, the piles are in the form of extruded structural sheet piles and are formed with male and female opposed edges so that similar sheet piles can be locked together at their adjacent side edges to form a continuous barrier or “cutoff” wall for blocking migration of subsurface fluids and/or surface fluids. Such barrier walls may also be utilized for seawalls, dikes, retaining walls, and other applications.
Sheet piles can be formed of various materials, including without limitation, polyvinyl chloride (PVC), high-density polyethylene (HDPE), or other plastics, fiberglass, composite, aluminum, steel or other metals, ceramics, and/or other materials. The most commonly used sheet piles typically have a Z-shape, Box-shape, or other corrugated cross-sectional profile to provide a measure of structural rigidity. Flat shaped sheet pile profiles are occasionally used in shallow driving depths or low lateral load applications. Regardless of their material and/or profile, however, sheet pilings are subject to buckling deformation during installation and/or from lateral loading. This buckling deformation typically increases exponentially as the length of the pilings increase.
A mandrel system can be utilized for installation of sheet piles when the depth the pile is to be driven and/or the hardness of the soil or other substrate through which the pile is to be driven exceed the structural ability of the piling to resist deformation. U.S. Pat. No. 7,056,066 and U.S. patent application Ser. No. 12/778,545, both incorporated herein by reference, disclose various apparatus and methods for installing sheet piles into a soil formation. Many known mandrel systems and installation methods, however, are limited by the passive attachment of the piling to the mandrel. For example, in deeper installations, the skin friction generated by the soil contacting the sheet piling can be greater than the passive gripping forces applied as the mandrel is driven into the soil. This limitation of the current systems and methods restricts the length of pile that can be installed and/or mandates the use of a much heavier pile than necessary.
Accordingly, it can be seen that needs exist for improved sheet piling systems and improved installation methods and apparatus for sheet piling systems. It is to the provision of systems, methods and apparatus meeting these and other needs that the present invention is primarily directed.